1. Field of the Invention
This invention relates to an improved process for reacting chlorine and mixtures of chlorine and sulfur dioxide with liquid or dissolved organic components. The process is particularly advantageous when the liquid phase to be treated shows or assumes an increased viscosity under reaction conditions. The process according to the invention is particularly suitable for the chlorination and sulfochlorination of fatty raw materials particularly fatty acids and/or esters thereof with monohydric and/or polyhydric alcohols. In the context of the invention, chlorination is understood to be both the addition of chlorine onto olefinic double bonds of the starting material and also the HCl-forming substitution reaction optionally activated by UV-light. Sulfochlorination is understood in the usual way to be the optionally UV-activated reaction of SO.sub.2 /Cl.sub.2 -mixtures with aliphatic chain constituents to form the SO.sub.2 Cl-group, the reaction being accompanied by the elimination of HCl.
2. Statement of the Related Art
The chlorination and sulfochlorination of fatty raw materials, particularly fatty acids and/or fatty acid esters, is known to lead to interesting fat-liquoring agents for leather and skins. Thus U.S. Pat. No. 3,988,247 and corresponding German patent 2,245,077 describe fat-liquoring agents such as these based on sulfonated chlorination products of natural or synthetic higher fatty acids or fatty acid esters in the form of their alkali, ammonium or amine salts, which are characterized in that they consist of sulfonated chlorination products which have been obtained by the chlorination of higher fatty acids or of esters of higher fatty acids having C.sub.8-24 chain lengths up to a chlorine content of from 20 to 45% by weight, the chlorination products containing virtually no more double bonds and the subsequent sulfonation step with SO.sub.3 having been carried out up to a content of from 40 to 100 mol % of SO.sub.3, based on chlorination product.
Corresponding fat-liquoring agents are also described in published German patent application 30 18 176 and are characterized in that they comprise sulfonated chlorination products which have been obtained by the sulfochlorination at 20 to 90.degree. C. of higher fatty acids or of esters of higher fatty acids having C.sub.8-24 chain lengths with chlorine and SO.sub.2, optionally under UV-light, up to a content of bound chlorine of from 5 to 30% by weight and a content of SO.sub.2 Cl-groups of from 1 to 20% by weight, the ratio of chlorine atoms to SO.sub.2 Cl-groups amounting to about 0.7-70:1, preferably 2-20:1, most preferably 2-7:1, followed by hydrolysis of those groups (saponification). An improvement is described in U.S. Pat. No. 4,451,261 (and corresponding German patent application 32 38 741). In this case, the starting materials used for producing the sulfonated chlorination products are higher fatty acid or fatty acid ester mixtures containing unsaturated fractions. In this process, chlorination is initially carried out up to saturation of the double bonds and is followed by sulfochlorination with chlorine and SO.sub.2. The subsequent hydrolysis step gives the required fat-liquoring agents.
Chlorine and SO.sub.2 are gaseous under the conditions of the chlorination/sulfochlorination reaction. In order to be able to react with the organic reactant, these gaseous components have to be dissolved in the liquid phase. To this end, the gases are normally passed upwards through gas distributors into a liquid column or gaseous and liquid reactants are passed in countercurrent to one another through exchange units, for example packed columns. However, it has been found that the viscosity of the organic liquid phase increases within increasing reaction time. At the same time, mass transfer between the liquid phase and the gas phase is increasingly inhibited. For example, in a column of the liquid reactant into which the gaseous reactants are introduced from below, increasingly larger bubbles which ascend very rapidly are observed with increasing viscosity of the liquid phase indicating a failure to react. The gaseous components delivered to the reactor leave the reactor unreacted to an increasing extent. The reaction velocity falls, influenced by the rate of transfer of the gases into the liquid phase. In the event of simultaneous absorption and reaction of several gases, the different solubility of the gases in the liquid phase affects the course of the reaction.